The invention relates to an apparatus and method for locating a device behind a wall or ceiling and, more specifically, the invention provides a device for defining the perimeter of a body rigidly mounted behind a wall or ceiling.
During the construction of buildings and structures, object or bodies are fixedly associated or rigidly mounted with respect to structural frame members such as wood or metal studs. After the bodies are mounted to the structural frame members, sheet material such as drywall, paneling or plywood is placed over the structural members, concealing the bodies mounted to the structural members. Before the building or structure is complete, the sheet material must be cut or pierced to expose the bodies. Generally, the bodies are used for communicating electricity to predetermined positions in the building.
The invention provides a locating device for defining a perimeter of a body rigidly positioned behind a sheet of material, such as an electrical box mounted to a stud and positioned behind a sheet of drywall, paneling or plywood. The locating device includes a first member that can be positioned in the body and has at least one magnet. The locating device also includes a second member that can be positioned on an outer surface of the sheet of material adjacent to the body. The second member includes at least one magnet and means to define the perimeter of the body with respect to the outer surface of the sheet of material. The magnet of the first member cooperates with the magnet of the second member to substantially align the perimeter defining means of the second member with the perimeter of the body.
The means for defining the perimeter of the body can define the perimeter of the body with respect to the outer surface of the sheet material before the sheet material is pierced. The means for defining the perimeter of the body can be a perimeter of the second member. For example, the second member can be shaped to substantially correspond to the shape of the body. A marking instrument can trace the perimeter or outline of the second member and thereby define the perimeter of the body. Alternatively, the means for defining the perimeter of the body can be an aperture defined by the second member. For example, the second member can be shaped with an arm that can rotate about the magnet. The aperture can pierce the arm. As the arm is rotated around the magnet, the aperture can guide a marking instrument for tracing a circle and defining the perimeter of a circular body behind the sheet of material. The invention can be practiced with a plurality of first members, each of the plurality of first members configured to engage a differently configured body. The arm of the second member can include a plurality of apertures, each of the plurality of apertures spaced from the magnet a distance corresponding to a perimeter of one of a plurality of differently sized bodies.
The first and second member can each include more than one magnet. The magnets of the first and second members can cooperate with a predetermined magnetic force operable to maintain the second member adjacent to the first member on the outer surface of the sheet of material. For example, if the first and second member are aligned so that perimeter defining means is aligned with the perimeter of the body, the second member can remained positioned on the outer surface of the sheet material, maintained in position by the magnetic force between the magnets of the first and second members. Also, the second member can have a predetermined weight to maintain the second member adjacent to the first member on the outer surface of the sheet of material when a magnetic force between the magnets of the first and second members is fixed. The weight of the second member can be modified by forming the second member with a cavity for receiving a weight member.
In embodiments of the invention were the first and second members each include more than one magnet, the magnets of the first magnet can be oriented with opposite polarity. For example, a first magnet of the first member can include an outwardly facing surface having a North polarity and a second magnet of the first member can include an outwardly facing surface having a South polarity. The second member can include two magnets similarly oriented. In such an embodiment of the invention, the alignment of the perimeter defining means of the second member with the perimeter of the body can be enhanced.